Required Practical 2

Question 1

Suggest why the student soaked the root tip in hydrochloric acid
2 marks

Answer 1

Break down links between cell/ separates cell.

Allow stain to pass / diffuse into cells

Stops mitosis

Answer 2

1. Select large number of cells / select cells at random;
2. Count number of chloroplasts;
3. Divide number of chloroplasts by number of cells:

Question 3

Stage two precautions required when working with hydrochloric acid

2 marks

Answer 3

1. Eye protection
2. Gloves
3. Add water to spills (immediately)
4. Do not pour away down sink

Question 4

Another student compares the mitotic index in the roots of two different species.

Give two considerations within her method to ensure this comparison is valid.

2 marks

Answer 4

1. Roots/plant of the same age;
2. Same growing conditions (for all roots);
3. Same distance from root tip;
4. Same time in acid

OR
Same temperature of acid;

5. Same concentration of acid;
6. Same pressure of squash;
7. Several fields of view (for each species);
8. Same time of day;